Everything in Scott McCall's life is starting to fall into place. He gets a spot on the First Line of his Lacrosse team and a date with the woman of his dreams. When he gets bitten by a werewolf, the people around him could be in danger.
Scott and Stiles discover that the werewolf curse can also be triggered by anger, besides the full moon. With the lacrosse game coming up, Jackson and his girlfriend, Lydia, hope to humiliate Scott. Will Scott be able to control his rage?
Scott is shaken when his vivid dream of a mauling aboard a school bus turns out to have actually happened. Scott turns to Derek for help, but Derek warns him that his help will not be free. Meanwhile, Scott's long awaited date with Allison turns into a group date. Scott gets bowling help from Allison.
Allison's aunt comes to town and shoots a shadowy werewolf figure with a special bullet that she estimates will kill it within 48 hours. Derek is the one hit and insists that Scott and Stiles help him.
Lydia and Jackson witness a werewolf attack at the video store. Stiles is worried for his father, the sheriff. Allison's aunt gives Allison a family heirloom and encourages her to use it to learn more about the family history. Scott and Allison play hooky on her birthday. Derek confronts Jackson about what he saw the night before. Derek gets a surprise visit. At the parent teacher conference, Scott's mom and Allison's father find out they both skipped school that day. After the parent teacher conference, someone pulls a gun and uses it.
Scott and Stiles are on the outs after Stiles' dad gets hurt, but when Derek insists that Scott avoid Allison, Scott turns to Stiles to help him master his anger with the help of a heart monitor. Meanwhile, Jackson is feeling the effects of having been scratched and approaches Allison claiming to want to get to know her and Scott better.
Responding to Scott's howl, the alpha savages Derek and traps Scott and Stiles in their high school. Events escalate even further when Allison, Jackson and Lydia are lured to the school as well with a phony text message.
As Scott's second full moon approaches, he gives in to his animal urges and hurts Stiles, but Stiles gets a measure of revenge in locking him up. Meanwhile, Jackson continues to try and get closer to Allison. The Argents learn that Scott somehow knew Derek.
Jackson discovers that he has aconite poisoning and thinks he has figured out what is up with Scott. Meanwhile, Derek hides from the manhunt in Stiles' room while Stiles and Scott try to get Allison's necklace and any clues that may lead to the identity of the alpha. Teammate Danny lends Stiles his internet expertise to help in the search.
The Alpha finally reveals himself to Scott and gives him an idea of why he has killed certain people. Argent stages an encounter thinking that Jackson may be a werewolf. Meanwhile, Allison discovers a bit more about her family's secrets and confronts Lydia about her kissing Scott.
Kate Argent has Derek chained up in a basement following her attack on his house and shows him off to Allison before torturing him. The coach has banned Scott from the Spring Formal in exchange for not dropping him from the team for academic reasons. Scott intimidates Jackson into escorting Allison to the dance, and she asks Lydia to escort Stiles.
After Allison sees her father, Chris Argent, fail in his attempt to run Scott down with his car, Chris Argent decides to send Allison and his sister Kate to Washington. Stiles convinces Peter Hale, who is the alpha werewolf, to spare Lydia's life after he bites her. Peter Hale agrees to Stiles' request, but in return Stiles must help him locate Derek. Meanwhile, Jackson is called to get Lydia to the hospital. Scott must cope with the girl he loves knowing his secret.